Thermostatic switch



Feb. 6, 1934. W, B GRH-"HTH 1,945,808

THERMOSTAT IC SWITCH Filed Nov. 3, 1952 FIG/J. ,f6 Z2 V5 Pfg@ we; 27 ia,

Patented Feb. 6, 1934 1,945,808 '.rnnaMos'rA'rrc SWITCH William B.Griiith, Audubon, N. J., assignor to Star Sprinkler Corporation,Philadelphia, Pa., a corporation of New Jersey Application November 3,1932. Serial No. 640,923

6 Claims. (Cl. 20G-137) My invention relates to improvements in athermostatic switch. and particularly relates to a switch forcontrolling an electric circuit for giving an alarm upon an increase oftemperature of the air in the event of a re within the zone in which theswitch is located.

The object of my invention is to provide a switch which will beactuatedby a sudden rate of rise of temperature and which also will beoperated at a fixed temperature.

A further object is to construct a switch having relatively movablethermal elements, actuated by a sudden rise of temperature, and alsohaving actuating means in the form of a part formed of metal, fusible ata predetermined temperature, which will insure the operation of theswitch, in the event of the failure of the relatively movable thermalelements to operate the switch. when the rate of rise of temperature isgradual. or slow, due to a smouldering fire.

A further object is to employ a thermal element in the form of a wire,and place the wireA under tension, by means of a metal strut fusible ata predetermined temperature.

A further object is to employ a thermal element in the form of twoparallel wires and provide a strut, in the form of a yoke, forequalizing the tension upon the wires.

A further object is to provide adjustable means for applying tensionupon one of the thermal elements, through an adjustable strut, or yoke.

A further object is to provide switching means in the form of aresilient member, which is iiexed from a normal position by a wire undertension, and also provide means fusible at a predetermined temperature,and forming a strut, or bridge, for deecting the wire out of a straightline, whereby the melting of the strut, or bridge, will release thetension upon the wire and allow the resilient member to return to itsnormal position for operating the switching means.

Myinventlon provides a device which is operable as a rate of rise oftemperature switch and also as a xed temperature switch.

Referring to the accompanying drawing, Fig. 1 is a vertical,longitudinal sectional view of a switch embodying my invention, andshowing the parts arranged for normally opening an electric circuit.Fig. 2 is a horizontal section on line 2-2 Fig. 1. Fig. 3 is atransverse, vertical section on line 3-3 Fig. 1.4 Fig. 4 is atransverse, vertical section on line 4--4 Fig. 1. Fig. 5 is a transversevertical section on line 5-5 Fig. 1. Fig. 6 is a. perspective view ofthe strut, formed of fusible material, detached. Fig. 7 is a viewsimilar to Fig. 1,I showing the switching means arranged for normallyclosing an electric circuit.

In the drawing, in which like reference characters refer to like parts,10 represents a frame, in the form of an elongated loop, consisting ofupper and lower longitudinal bars 12 and 13 and endmembers 14 and 15.

A resilient member in the form of a plate spring 16, has one end thereofsecured in the end member 14 of the frame. Said end member 14 isprovided wth a transverse recess to' receive the end of the plate 16,which latter encircles a bolt 18, mounted in said recess of the frame.The bolt 18 forms a terminal, or binding post, for the oonnection of anelectric conductor 19, as shown in Fig. 1.

The bars 12 and 13 of the frame form one of the thermo elements of theswitch. The other thermo element of the switch consists of an extremelyfine wire, or wires, which will increase in length relatively to thebars of the frame, when subjected to a sudden rise of temperature.

The wires 20 and 21, shown in the drawing, form one of the thermoelements. Said wires are attached to the free end of the resilientmember 16, and they are also attached to the end member 15 of the frame.I A

The wires 20 and 21 form tension members, as they are placed undersuilicient tension to flex the resilient member 16 from a normalposition into the ilexed position, shown 1n the drawing, .by means of astrut 22. Said strut forms a bridge which holds the wires out ofalignment between the points of attachment for the ends of the wires.

The strut, or yoke 22 is formed of metal fusible at a predeterminedtemperature, and when melted will release the wires and the resilientmember 16 from the tension. thus allowing the member 16 to operate theswitching means controlling an electric circuit for giving an alarm.

The strut, or yoke 22, shown detached in Fig. 6, comprises end membersor arms 23, which rest upon the wires 20 and 21. and a depending centralportion 24, provided for spreading the wires, as shown in Figs. 2 to 5.

An adjusting screw 26 is threaded in an aperture formed through anenlarged boss 27 formed upon the upper bar 12 of the frame. The screw 26is provided with a point 28 which engages the central portion of theyoke 22. Anenlarged head 29 upon the screw 26 provides means for turningthe same for placing sufficient tension upon the wires to ilex themember 16 and also deflect the wires 20 and 21 out of a straight line.By means of this novel construction, the wires may be'placed l ya underequal tension, as the tilting of the strut or yoke 22 upon the point ofthe screw 26 will equallze the tension upon the wires.

A fulcrum part 30 is formed upon a screw 31,

secured in an enlarged boss 32 formed upon thebar 13 of the frame. Thescrew 31 is of the nllister head type, and the part 30 consists of a natplate secured in the slot formed in the head of the screw. The screw 31is electrically insulated from the frame by insulating material 33. Saidscrew 31 forms a terminal, or binding post, for the connection of theelectrical conductor 35.

The fulcrum part 30 forms a contact point with which the member 16 makescontact when flexed, as shown in Fig. 1, and completes an electriccircuit between the conductors 19 and 35.

The fulcrum part 30 forms a bridge over which the member 16 is flexed bythe tension placed upon the wires 20 and 21 by the strut 22, whichlatter also forms a bridge for deiiecting the wires between the fulcrumpart and the end 15 of the frame.

The switching means, shown in Fig. 1, forms a closed electric circuitbetween the conductors 19 and when the resilient member 16 is exed bythe tension upon the wires 20 and 21. When the tension upon the wires isreleased the member 16 moves toward its normal position and out ofcontact with the plate 30 on the screw 31, thus opening the circuit.

The lower bar 13 of the frame is provided with an enlarged lug forming abase 36. for the attachment of a casing 38. I'he casing 38 is attachedto said base by means of a screw 39, which engages a sleeve 40, formedof insulating material, and secured in an aperture formed in the base36, by a set screw 42, shown in Figs. 2 and 3. 'Ihe base 36 is alsoinsulated from the casing by a sheet ofinsulatlng material 43.

The lower surface of the base 36 is formed with a cylindrical surfacecorresponding to the shape of the casing 38, as shown in Fig. 3. By thisconstruction the frame 10 is self centering within the casing 38, andthey may be secured together by means of one screw, thus making thecasing readily detachable from the frame.

The casing 38 is provided with flanges 45 by which it may be secured toa ceiling, or wall. The casing is formed of metal having perforationsfor the free circulation of air, whereby any changes in thetemperature-oi the surrounding air will aifect the thermal elements.

The switching means shown in Fig. 7, is constructed for maintaining anopen electric circuit. A resilient member has one end thereof secured inthe end oi' the frame l0. When the free end of the member 50 is i'iexedby the tension upon the wires 20 and 21, it is held out of contact withthe terminal 61, thus opening the circuit. When the tension is releasedthe member 50 moves toward its normal position and makes contact withthe terminal 51, which latter is electrically inlilated from the frame,and is connected with the conductor 52 of the electric circuit. Theother conductor 53 is electrically connected with the frame by means ofthe bolt 54. which latter is not insulated from the frame. The member 50is electrically connected .with the conductor 63 through the frame aswell as through the bolt 54.

The longitudinal bars 12 and 13 of the frame 10 are of large diameter sothat sudden changes in the temperature of the surrounding air will actslowly upon the frame and will not increase its length within a shortperiod of time. 'Ihe wires 20am! 21 areextremelysmallindiameter andlwill be quickly increased in length when a rapid rise in temperature inthe surrounding air takes place.

The frame 10, and the wires 20 and 21, ibrm relatively movable thermalelements. which will hold the resilient member 16 in the flexed positionduring slow changes in the temperature of the air. In the event of ilrethe air will be increased in tempera-ture, andshould the rate o! rise intemperature be sudden the thermal element, comprising the wires 20 and2l, will expand rapidly, relatively to the frame, and release thetension of the wires upon the resilient member, which latter will movetoward its normal position and actuate the switching means forcontrolling the electric circuit for giving an alarm.

In the event of a slow smouldering tire, the rate of rise o! thetemperature of the air surrounding the device may be so slow that thethermal elements will not have sufilcient relative movement to allow theresilient member to move into the operative position, in which event thestrut 22, which is made of metal fusible at a predetermined temperature,will melt and release the tension upon the wires 20 and 21 and `thusallow the resilient member to move toward its normal position andoperate the switching means for giving an alarm.

My novel thermostatic switch will operate as a rate of rise oftemperature device for giving an alarm in the event of a fire causing asudden increase of temperature and will also operate as a xedtemperature device when the temperature is slowly increased to apredetermined temperature.

I claimz- 1. A thermtatic switch having in combination a resilientmember normally assuming one position and adapted to be ilexed from itsnormal position, switching means controlled by said member when thelatter is in its normal and flexed positions, relatively movable thermalmembers operatively associated with said resilient member and arrangedfor holding the latter in the flexed position under normal temperaturesand i'or permitting the resilient member to assume its normal positionupon a sudden rise in temperature. and actual the switching means, and apart formed of metal fusible at a predetermined temperature aranged forapplying tension to one of said thermal members at temperatures belowsaid predetermined temperature and for releasing the tension upon saidlast mentioned thermal member upon the fusing of said part.

2. A thermostatic switch having in combination a resilient membernormally assuming one position and adapted to be iiexed from its normalposition, switching means controlled by said member when the latter isin its normal and if exed positions, a thema! tension member responsiveto a sudden rise of temperature, said tension member connected with saidresilient member and arranged for holding said resilient member in theflexible position under normal temperatures and for permitting theresilient member to assume said normal position upon a sudden rise intemperature, and a strut formed of metal fusible at a predeterminedtemperature arranged for deiiecting said tension member from a normalposition at temperatures below said predetermined temperature and forreleasing the tension upon said tension member upon the fusing oi' thestrut.

3. A thermostatic switch having in combination a resilient membernormally assuming one position and adapted to be flexed from its normalposition. switching means controlled by said member when the latter isin its normal and flexed positions, a thermal tension member responsiveto a sudden rise of temperature. said tension member connected with saidresilient member and arranged for holding said resilient member in theilexed position under normal tem.- peratures and for permitting theresilient member to assume said normal position under a sudden rise intemperature, a strut formed of metal fusible at a predeterminedtemperature, and means adiustably mounting said strut relatively to thetension member arranged for applying tension to the tension member attemperatures below said predetermined temperature and for releasing thetension upon said tension member upon the fusing of the strut.

4. A thermostatic switch having in combination, a frame, a resilientmember mounted upon the frame and adapted to be flexed from its normalposition, switching means controlled by said member when the latter isin its normal and ilexed positions, a thermal responsive memberconnected with said resilient member and forming a thermal elementmovable relatively to the frame and responsive to a sudden rise oftemperature, and a part formed of metal fusible at a predeterminedtemperature mounted upon the frame and arranged for applying tension tosaid thermal member at temperatures below said predeterminedtemperature, and for releasing the tension upon said thermal member uponthe fusing of said part.

5. A thermostatic switch comprising a frame formed of longitudinal barsand end members connecting said bars, a resilient member secured in oneof said end members, wires attached to said resilient member and to theopposite one of said end members, a strut formed of metal fusible at apredetermined temperature, said strut located upon the wires and forminga bridge located between the opposite points of attachment of saidwires, means adjustably mounted upon the frame and engaging said strutfor applying tension to the wires, and contact y members mounted uponthe frame and located in operative relation with said resilient member.

6. A thermostatic switch comprising a frame formed of longitudinal barsand end members connecting said bars, a resilient member secured in oneof said end members, wires attached to said resilient member and to theopposite one oisaid end members. a strut formed of metal fusible at apredetermined temperature, said strut located upon the wires and forminga. `bridge located be tween the opposite points of attachment of saidwires. means adjustably mounted upon the frame and engaging said strutfor applying tension to the wires, contact members mounted upon theframe and located in operative relation 'with said resilient member, abase formed upon said frame, a casing enclosing the frame and fasteningmeans detachably securing the casing to the frame.

WILLIAM B. GRIFFITH.

